Microwave Resonant Sensing of Dielectric Changes in Myotubes Exposed to C26 Tumor-Conditioned Medium

Microwave biosensing offers a fast and label-free approach to monitor cellular properties in vitro, with potential applications from drug screening to development monitoring. Here, we present a circular patch resonator optimized for the measurement of murine skeletal muscle myotubes' dielectric properties. To assess sensor's sensitivity, the alterations due to the presence of myotubes in standard dishes were initially assessed in comparison to growth medium (GM) only. Subsequently the sensor was tested for its capability to capture alterations in myotubes treated with C26 tumor-conditioned medium, as a representative case-study of all the alterations that may involve myotubes in pathological conditions or during pharmacological treatments. Two stable resonance peaks were consistently observed in all the three groups, but significant changes in the peaks' attenuation, frequency or shape were reported across the groups, reflecting subtle changes in the dielectric properties of the cells. The sensor reliably captured these differences in a label-free, non-invasive manner, demonstrating its potential for high-throughput monitoring of cellular states and paving the way for scalable, industrial-ready microwave biosensing platforms.